Is it possible to simulate an optical fiber with cycles?
if you just want to have the looks of fiber optics, faking it is a much easier approach.

But this is definitely an interesting experiment for Cycles. It was surprisingly easy to achieve the result:



A few things I learned:


the fiber needs to be a volume. Make sure the two ends are closed.
Just like a real FO, too much kink in the fiber will kill the internal reflection.
I tried to model the core(high IOR) and the cladding(low IOR) as separate geometry, that didn't seem to work too well. I just ended up using only the core (and basically using air to model the cladding material)
Render with lots of bounces. High sample value helps make the image smoother, but if the bounce value is too low, no light will come out of the fiber.


Blend File